[syzbot] [bpf?] KASAN: slab-out-of-bounds Read in atomic_ptr_type_ok

From: Kohei Enju
Date: Sat Mar 15 2025 - 02:00:13 EST


> syzbot tried to test the proposed patch but the build/boot failed:
>
> failed to apply patch:
> checking file kernel/bpf/verifier.c
> patch: **** unexpected end of file in patch

Oh, something wrong with format, such as trailing space...?

#syz test

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 3303a3605ee8..0120cc325078 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -7788,6 +7788,12 @@ static int check_atomic_rmw(struct bpf_verifier_env *env,
static int check_atomic_load(struct bpf_verifier_env *env,
struct bpf_insn *insn)
{
+ int err;
+
+ err = check_load_mem(env, insn, true, false, false, "atomic_load");
+ if (err)
+ return err;
+
if (!atomic_ptr_type_ok(env, insn->src_reg, insn)) {
verbose(env, "BPF_ATOMIC loads from R%d %s is not allowed\n",
insn->src_reg,
@@ -7795,12 +7801,18 @@ static int check_atomic_load(struct bpf_verifier_env *env,
return -EACCES;
}

- return check_load_mem(env, insn, true, false, false, "atomic_load");
+ return 0;
}

static int check_atomic_store(struct bpf_verifier_env *env,
struct bpf_insn *insn)
{
+ int err;
+
+ err = check_store_reg(env, insn, true);
+ if (err)
+ return err;
+
if (!atomic_ptr_type_ok(env, insn->dst_reg, insn)) {
verbose(env, "BPF_ATOMIC stores into R%d %s is not allowed\n",
insn->dst_reg,
@@ -7808,7 +7820,7 @@ static int check_atomic_store(struct bpf_verifier_env *env,
return -EACCES;
}

- return check_store_reg(env, insn, true);
+ return 0;
}

static int check_atomic(struct bpf_verifier_env *env, struct bpf_insn *insn)
--
2.48.1